﻿namespace homework1

{

    internal class Program

    {

        static void Main(string[] args)

        {

            int count = 0;

            for (int i = 1; i <= 4; i++)

            {

                for (int j = 1; j <= 4; j++)

                {

                    for (int k = 1; k <= 4; k++)

                    {

                        if (i != j && i != k && j != k)

                        {

                            int num = i * 100 + j * 10 + k;

                            Console.Write(num + " ");

                            count++;

                        }

                    }

                }

            }

            Console.WriteLine($"\n能组成 {count} 个互不相同且无重复数字的三位数");

        }

    }

}

​